Cary Institute scientists help lead the National Climate Assessment

Tuesday, February 26, 2013

On January 14, a week before President Obama said Americans must respond to climate change in his inauguration speech, a draft of the 2013 National Climate Assessment (NCA) was released.

Four years in the making, the comprehensive analysis summarizes current global change trends and makes predictions for the coming years. Three members of the Cary Institute’s community played a leadership role in the report’s creation.

Jerry Melillo, vice-chair of the Cary Institute Board of Trustees and senior scientist at the Marine Biological Laboratory of Woods Hole, spearheads the effort as chair of the National Climate Assessment and Development Advisory Committee. Cary Institute President William Schlesinger and microbial ecologist Peter Groffman led sections on biogeochemistry and ecology respectively.

The Global Change Research Act of 1990 requires periodic National Climate Assessment (NCA) reports to analyze the effects of global change on the environment, agriculture, energy production and use, land and water resources, transportation, human health, and biological diversity. The report’s goal is to inform policy decisions and educate citizens about climate change impacts.

“The NCA helps us see if predictions made over time have come to pass and lets us learn from what we didn’t get right,” notes Groffman. New perspectives, gained by incorporating refinements from earlier editions, Groffman says, make the NCA critically valuable to the scientific community.

Groffman’s section focused on ecosystems, ecosystem services, and biodiversity, with participants analyzing phenomena ranging from species loss to changes in the arrival of spring and fall. Synthesizing research from hundreds of documents, testing predictions, and refining current knowledge “offers a more robust assessment, which will ultimately lead to better decision making,” states Groffman.

Schlesinger, who led the group on biogeochemical cycles, recognizes that some refinements in his section may not sit well with various stakeholders. “Previously, some scientists thought that upwards of 35% of carbon dioxide emissions were being absorbed by North American forests. Current findings indicate that 24% is the high bar, and 13% is more accurate.”

His section confirms that CO2 emissions from fossil-fuel use continue to be the major driver of climate change. It also notes that estimates of human-derived nitrogen emissions have nearly doubled.

The nitrogen cycle’s influence on climate change is complex. Nitrogen gases and aerosols in the atmosphere may be moderating climate warming at present, but the increasing use of nitrogen fertilizers is likely to enhance greenhouse warming over the next 100 years.

Under Melillo’s guidance, an important feature distinguishing this NCA report from prior editions is input from both public and private sectors. That the foundation of the 2013 report is built on partnerships among the government, academics, and industry may enhance meaningful integration into policy decisions.